The tachometer in my '88 has been on the fritz for several months now. Sometimes it works, sometimes it doesn't. It bounces even when it is displaying an RPM reading. I never gave it much thought because the truck seems to still drive fine, but now I'm starting to wonder.

I am familiar with the problems a bad tach sensor can cause to an automatic transmission, but because mine is a 5-speed, does the tach sensor contribute to anything other than the tachometer reading? Can I expect anything (other than the tachometer display) to change if the sensor is bad and I replace it?

 

Nope, on a 5speed truck it's only for driver information.

 

Perfect. Thanks

 

Often you can get the old sensor to work by removing it, cleaning the business end, then reinstalling it. The pickup is magnetic and picks up particles and gunk over time.
There's also a couple of good write ups in the FAQ from a couple of members that made their own replacement sensors.